Yep, you need the new USB cradle. Then I find PowerAgent is kind of weird on my new Powerbook, and I do have to do things in one particular order: (1) load up PA (2) then plug in the cradle, (3) click on my name on PA (4) then put the unit on the cradle and turn it on so it shows Host. If I mess with the order, it does not recognize the PT.

I think PA sucks, however, and since moved to the trial version of CyclingPeaks WKO+, which needs either the PC in Windows or you have to load Parallels, VM whatever or Bootcamp to boot your Mac into Windows. But WKO+ is so much better that I will use on my PC if I have to.